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Kevlar Hulls

Discussion in 'General Yachting Discussion' started by 993RSR, Dec 30, 2020.

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  1. 993RSR, Dec 30, 2020
    #1
    993RSR

    993RSR Senior Member

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    I am interested in a sailboat that was custom built in 1984. Below is the designers description of the build on this particular boat (one off).
    I know Kevlar is tough to repair. Beyond that does it absorb moisture or breakdown with age?


    Our experience in design and construction with high quality, hi-tech Kevlar laminates and the resultant reduction in the premium paid for use of this race boat technology, now makes it extremely viable and desirable for construction of high quality cruising yachts. This design calls for a predominantly Kevlar laminate throughout and utilizing a thick high density Divinycel core which gives both high strength and stiffness, as well as, good thermal insulation and exceptional impact strength.

    Interior joinery is honeycomb cored wherever possible and the resulting weight savings in the interior and the total structure have enabled a 45% ballast ratio in a relatively light displacement boat carrying a fully fitted luxury interior. The rig chosen is interesting in itself, in that it features a masthead rig with short J and long E. This reduces the size of the head sails assuring of handling the rig and provides a mainsail large enough to realistically handle the boat under mainsail only. The rig size is actually quite large, giving a sail area displacement ratio of 21.3 which strikes a compromise between the yachts racing and cruising demands.
  2. d_meister, Dec 30, 2020
    #2
    d_meister

    d_meister Senior Member

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    More research would be a good idea. As I recall, early attempts at replacing glass fiber with kevlar were problematic as the resins didn't adhere well to the slippery plastic Kevlar. An article HERE.
  3. Slimshady, Dec 30, 2020
    #3
    Slimshady

    Slimshady Senior Member

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    My parents were the first that I know of to use kevlar in boat construction. Lydia yachts boats were primarily mahogany plank with glass inside and out. Kevlar was used for puncture resistance. A lydia motor sailor was t boned by an aluminum strike sportfish in palm beach inlet decades ago. Strike needed 10' of bow replaced. Lydia broke a stay and needed cosmetic repairs but structurally intact. Neither boat took on water according to captains. Paul spencer doesn't use it in his builds because of adhesion issues and doesn't feel it is worth the effort. Roy Merritt does use it. Hope this helps.
  4. SkyDriver, Dec 30, 2020
    #4
    SkyDriver

    SkyDriver Member

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    Intrepid has used Kevlar for many years.
    I think it was a option.
    Currently, don't know if they are still using it.
    You can always call Intrepid & talk to customer service.
    Hope that helps.
    :)
  5. Capt J, Dec 30, 2020
    #5
    Capt J

    Capt J Senior Member

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    Kevlar can be a very good material. But I always head impact resistance wasn't it's strong suit. That being said, kevlar is very noisy, transmits a lot of noise.
  6. YachtForums, Dec 30, 2020
    #6
    YachtForums

    YachtForums Administrator

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    True about noise, but impact resistance is a trademark of Kevlar. Downside is getting resin to wick.
  7. Capt Ralph, Dec 30, 2020
    #7
    Capt Ralph

    Capt Ralph Senior Member

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    Kevlar?
    Ha !!
    I remember Avanti and others that could not lay Kevlar and thinned the juice with Acetone....
    **** started peeling like a rotten banana within months.

    Any retail production hull that has Kevlar in it I laugh at.
  8. Fishtigua, Dec 31, 2020
    #8
    Fishtigua

    Fishtigua Senior Member

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    Most hulls are now a blend of Carbon/Kevlar. We had a race boat that was a blend, pretty unbreakable even over 85 kn.
  9. JWY, Dec 31, 2020
    #9
    JWY

    JWY Senior Member

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    Below is a quote from the YF review I wrote on the Elling 49. You can see an incredible picture at the end of the review:
    https://www.yachtforums.com/review/elling-49-e4.22489/

    "How tough is this boat? Unfortunately the bragging rights of the Elling construction were tested … and proven. An owner crashed his Elling into a concrete bridge at a speed of 14 knots. All woodwork in the forward cabin was completely crushed as was the glass fiber in the laminate – however, the Kevlar was still intact. Although the front of the yacht was completely weakened and soft, water didn’t penetrate the Kevlar layer. The vessel returned to the yard on its own bottom where repairs were completed in time to display the yacht at an upcoming boat show. Now that’s a testimonial!"
  10. Capt J, Dec 31, 2020
    #10
    Capt J

    Capt J Senior Member

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    I surely hope they didn't sell that boat to anyone!!!!
  11. SeaEric, Jan 4, 2021
    #11
    SeaEric

    SeaEric YF Historian

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    Just as a general FYI - It is my understanding that Kevlar material will peg a moisture meter.
  12. 993RSR, Jan 4, 2021
    #12
    993RSR

    993RSR Senior Member

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    Yes I have experienced that meter issue in the past. This particular boat was built by Concordia in 1984. Any hull issues should be apparent by now. She has done at least 30 offshore races over 500 miles. Concordia has a very good reputation for quality in recent years.
    A core sample may be the only way to confirm the hulls health. The surveyor can decide.